This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In prior studies, SDF-1 has been shown to play a significant role in shoulder inflammation, subacromial bursitis and rotator cuff disease. In order to determine the potential biologic efficacy of SDF-1 inhibitors in treating shoulder inflammation, these studies will utilize a rotator cuff injury model in the rat. The specific aims of this project are to examine the biologic effect of SDF-1 pathway inhibitors AMD 3100, T140 analog (4F-Benzoyl-TN14003) and CTCE-9908, on reducing inflammation and their effects on rotator cuff tendon healing. We hypothesize that SDF-1 inhibitors will decrease inflammation in the subacromial bursa, but will not inhibit rotator cuff tendon healing. Specific Aims 1. Effect of SDF-1/CXCR4 Inhibitors on Local Inflammation in the Rat Shoulder: The morphological and biochemical effects of SDF-1/CXCR4 receptor inhibitors (AMD3100, T140 analog and CTCE-9908), and antibodies to CXCR4 (MAB171 and 12G5) will be examined in rats with subacromial inflammation induced by rotator cuff injuries. Male Lewis rats will undergo surgery to mimic a rotator cuff injury of the infraspinatus tendon and to induce inflammation (bursitis) in the adjacent subacromial bursa. Inhibitors will be systemically administered via implanted osmotic minipumps. After sacrificing the animals, subacromial bursa will be harvested and SDF-1, interleukin-1 (IL-1), and tumor necrosis factor (TNF-alpha) expression will be measured by quantitative PCR and enzyme linked immunosorbent assay (ELISA). Histologic evaluation for subacromial inflammation and immunohistochemistry will also be performed to assess the effect of SDF-1 blockade on the local inflammatory response. 2. Effect of SDF-1/CXCR4 Inhibitors on Rotator Cuff Tendon Healing in the Rat Shoulder: The morphological, biochemical, and biomechanical effects of SDF-1/CXCR4 receptor inhibitors, (AMD3100, T140 analog and CTCE-9908), and antibodies to CXCR4 (MAB171 and 12G5) on rotator cuff tendon healing will be examined in rats with rotator cuff injuries. (see above) After harvesting rotator cuff tendons from the site of injury, tendon healing will be assessed histologically and by local expression of type I and III collagen. Tendon strength will be assessed using an MTS 810 servohydraulic load frame (MTS Corp, Eden Prairie, MN). The insertion and attachment sites of the supraspinatus tendon will be embedded rigidly in urethane (Smooth On, Easton, PA) and subjected to monotonic loading in axial tension at a constant displacement until failure. From the MTS load-displacement tracing, the yield load, maximum failure load, linear stiffness, displacement to yield and displacement to failure will be calculated.